Electrical motor drives are known per se. A quality of workpieces, which are by way of example machined by production machinery employing such motor drives, is clearly dependent on a circularity (radial runout) of the rotational motion of a shaft driven by the motor and/or a workpiece attached thereto. A corrugation or undulation of the rotational speed or angular speed, and depending thereon an accuracy of a desired rotational position or angular position, are determined by the quality of the control circuit, more particularly by the quality of the closed loop comprised in the control circuit, the driven load, and interferences. The latter can be distinguished in static interferences and methodic interferences. Static interferences occur as a matter of principle. Furthermore, the occurrence of static interferences is periodical or cyclical, when the underlying motion is either a uniform motion or a repetitive motion. Static or cyclic interferences thus can be perceived as a speed-dependent disturbance, where specifically a frequency of such cyclic interferences is dependent of the speed of the rotational motion.